Mike Cohn - background

Transcription

1 Agile Estimating and Planning 1 Mike Cohn - background 2

2 What s a good plan? A good plan is one that supports reliable decision-making Will go from We ll be done in the fourth quarter We ll be done in November We ll be done November 7th 3 What makes planning agile? 4

3 An agile approach to planning Feedback Feedback 5 Agenda 6

4 7 Which we re talking about Product Backlog Iteration Backlog Iteration 2 Iteration 1 8

5 How long will it take......to read the latest Harry Potter book?...to drive to Seattle? 9 Estimate size; derive duration 10

6 Measures of size Traditional and agile measure size differently Traditional measures of size Lines of Code Function Points Agile measures of size Story points Ideal days 11 Story points The bigness of a task Influenced by How hard it is How much of it there is 5 Relative values are what is important: A login screen is a 2. A search feature is an 8. Points are unit-less 12

7 Dog points Assign dog points to the following breeds 13 14

8 Ideal time How long something would take if it s all you worked on you had no interruptions and everything you need is available The ideal time of a football game is 60 minutes Four 15-minute quarters The elapsed time is much longer (3+ hours?) 15 Elapsed time vs. ideal time Ideally But instead... 16

9 Ideal time vs. elapsed time It s easier to estimate in ideal time It s too hard to estimate directly in elapsed time Need to consider all the factors that affect elapsed time at the same time you re estimating 17 Specialization First, don t worry about it too much We re usually better off with fairly rapid, imprecise estimates than spending more time Second Just add up the components and report one total estimate of ideal days = 8 = 8 = 8 18

10 The great debate Which do you prefer: 19 Comparing the approaches Story points help drive cross-functional behavior Story point estimates do not decay Story points are a pure measure of size Estimating in story points is typically faster My ideal days cannot be added to your ideal days Ideal days are easier to explain outside the team Ideal days are easier to estimate at first Ideal days can force companies to confront time wasting activities 20

11 What I usually do 21 Three levels of planning

12 ...three levels of precision Product Backlog Iteration Backlog Iteration 2 Iteration

13 Estimate by analogy Comparing a user story to others This story is like that story, so its estimate is what that story s estimate was. Don t use a single gold standard Triangulate instead Compare the story being estimated to multiple other stories 25 Triangulation Confirm estimates by comparing the story to multiple other stories. Group like-sized stories on table or whiteboard Story 3 26

14 Disaggregation Breaking a big story into smaller stories or tasks You know how long the smaller tasks take So, disaggregating to something you know lets you estimate something bigger you don t know Sometimes very useful But disaggregating too far causes problems Forgotten tasks Summing lots of small errors can be big number 27 How much effort? A little efforts helps a lot A lot of effort only helps a little more Accuracy Effort 28

15 Use the right units Can you distinguish a 1-point story from a 2? Can you distinguish a 17 from an 18? Use units that make sense, such as 1, 2, 3, 5, 8 1, 2, 4, 8 Stay mostly in a 1-10 range 29 Planning poker An iterative approach to estimating Steps Each estimator is given a deck of cards, each card has a valid estimate written on it Customer/Product owner reads a story and it s discussed briefly Each estimator selects a card that s his or her estimate Cards are turned over so all can see them Discuss differences (especially outliers) Re-estimate until estimates converge 30

16 Planning poker - an example Estimate these 32

17 Why planning poker works Emphasizes relative estimating Focuses most estimates within an approximate one order of magnitude Everyone s opinion is heard Estimators are required to justify estimates It s quick It s fun 33 34

18 Product Backlog Iteration Backlog Iteration 2 Iteration 1 35 Two approaches Velocity-driven iteration planning We finished 15 story points last time, let s plan on 15 story points this time. Commitment-driven iteration planning 36

19 Commitment-driven iteration planning Discuss the highest priority item on the product backlog Decompose it into tasks Estimate each task Whole team estimates each task Ask ourselves, Can we commit to this? If yes, see if we can add another backlog item If not, remove this item but see if we can add another smaller one 37 Estimate availability 38

20 It looks something like this 39 1 time 2 time 40

21 41 Initial velocity Three ways to come up initial velocity Express velocity as a range that matches your uncertainty in it 42

22 Forecasting velocity Just like commitment-driven iteration planning Estimate available hours for the iteration Pick a story, break into tasks, estimate each task Repeat until full Ideally, plan more than one iteration 43 44

23 45 Release planning Release Plan 46

24 An example with velocity=14 47 Updating the release plan Revisit the release plan at the end of every iteration Update it based on: Current understanding of velocity Current prioritization of the product backlog This should be a very short and sweet process 48

25 Changing the release plan 49 Look at velocity in a few ways Velocity Last Observation = 36 Mean (Last 8) = 33 Mean (Worst 3) = Iterations 50

26 Extrapolate from velocity At our slowest velocity we ll finish here At our long-term average we ll finish here At current velocity we ll finish here 51 Updating the release plan 25 Velocity Mean of Worst 3 Most Recent Long-term Average = = = Iterations 52

27 Update this release plan 6 worst 3 = 6 average of last 8 = 6 average of last 8 = Running Total Estimate Story 5 5 As a user, I can As a user, I can As a user, I can As a user, I can As a user, I can As a user, I can As a user, I can As a user, I can As a user, I can As a user, I can As a user, I can As a user, I can Upcoming public classes 54

28 Mike Cohn contact info 55